layer.conf: add "dunfell" compatibility
layer.conf: add "dunfell" compatibility

Update the layer compatibility information to indicate this layer is
compatible with "dunfell".

Signed-off-by: Diego Rondini <f48a046fa74db96735a4084e98d9bb18d62ce377@kynetics.com>

linux-sunxi/meta-sunxi,linux-sunxi/meta-sunxi,linux-sunxi/meta-sunxi,net147/meta-sunxi,net147/meta-sunxi